Numerical Simulation And Optimization Of Fluid Flow, Combustion And Heat Transfer In Heating Furnace

Based on an experimental heating furnace with a self-designed low NOx gas fired burner, this paper is aimed at solving the problems widely existing in practical operation of heating furnace. The flowing of gas, heat transfer among gases, and combustion in the furnace are fully studied by experimental measurement and numerical simulation through combing the knowledge of heat transfer, mass transfer, momentum transfer and chemical reactions. The model using software Fluent is verified and modified by experimental data. The distribution of temperature and the composition of the gas in the furnace are studied by the modified numerical model, then the influence on the distribution of temperature and the exhausted NOx in the furnace by operation parameter and circulation flow gas are studied and analyzed. The principal contents of this paper are as following:(1) Through the analysis of experimental test, the results show that the content of inflammable composition is low, the fuel burns with perfect combustion, and the mixture of the fuel and the auxiliary air is reasonable. The NOx in the exhaust gas is not more than 60ppm in average, which is lower than that of national emission standard. It is benefit to control combustion pollution. The temperature distribution in the furnace is uniform relatively, the furnace temperature deviation is not more than 30K, which can meet the requirement of high efficient combustion and improve the quality of workpiece.(2) Based on the boundary conditions such as the flux, temperature of the fuel and auxiliary air by experimental test, the numerical simulation model combined with the standard k-εturbulence model, the eddy dissipation combustion model, DO radiation model and the formation of NOX model is established to simulate the flow of gas, the combustion and heat transfer in the furnace;(3) The field of the gas flow, temperature and composition of the fuel gas are analyzed by the simulation of the furnace. It is showed that circumfluence is appeared around the burner, together with the eddy produced by circumfluence, which brings on stable combustion and intense mixture of the gas. The temperature of the furnace is relatively uniform and the temperature deviation of the furnace is small, which is benefit for heating workpiece. The NOX emission in the exhaust gas is small too. The simulation results are verified by the experimental date, and they have the same tendency, which can provide a good reference to the optimization parameters.(4) The influences on the temperature distributions and NOx emissions by different operation parameters are studied with various coefficient of air consumption, preheated air temperature and ratio of the outer auxiliary air to the core auxiliary air. The reasonable operation parameters are decided, which are important reference data for organizing high temperature gas fluid flow and combustion in heating furnace. The results can be further extended to the same type thermal furnace to achieve the purpose of energy saving.